Patent GB-473568-A (GB)
Title: Improvements relating to hydraulic pressure system for operating accessories of automotive vehicles
IPC: B60T13/14
Filed: 1936-06-11
Abstract: 473,568. Fluid-pressure brakes ; fluid - pressure servomotors ; hydraulic accumulators; electric switches. ROCKWELL, E. A. June 11, 1936, No. 16311. Convention date, June 27, 1935. [Class 103 (i)] [Also in Groups XXIX and XXXVII] A hydraulic system for operating the brakes, clutches, &c. of motor vehicles comprises a source of pressure liquid maintained at constant pressure and adapted to be connected to an actuator through a valve device comprising a movable valve and valve seat connected to a member operated by the operator, the force exerted by the actuator being in accordance with the force exerted by the operator which may also be simultaneously applied directly to the brake &c. A brake operating system comprises a hydraulic cylinder 46, with a piston 50 engaging arms 77 on a sleeve 77a pivoted in a casing 37 and carrying an arm 78 connected at 20 to a link 19 extending to a brake shaft. A floating lever 21 is connected at 20 to arm 78, at 22 to a link 23 extending to the pedal and by a link 33 to an arm 35 on a shaft 36 having a valve-operating arm 76. The lever 21 has an adjustable pin-and-slot connection 34 with the link 33. A tubular slide-valve 67 disposed in the piston 50 has radial ports 70 and an annular recess 71 adapted to register with a chamber 57 connected to the pressure liquid supply through chamber 51 and pipe 48. An exhaust discvalve 72 seating on valve 67 is engaged by the arm 76 through a member 73. A pressure liquid accumulator and pump unit, Figs. 4, 6, 9, comprises a pair of gear wheel pumps operating in series and housed respectively in plates 114, 126 between spacer members 118, 129 in a casing 83. One wheel 116 of each pump is secured to shaft 104 of an electric motor 100. The pumps draw liquid from a reservoir 82 through passage 98 and deliver it to the accumulator chamber 141, driving the piston 145 and a disc 147 against the resistance of springs 97 surrounding tubular guides 96 for the disc. The exhaust liquid from the cylinder 46 enters the reservoir through pipe 81 and is filtered by passing through a tubular piece of cloth 89 secured to a head 90. When the piston 145 reaches a predetermined point a button 148 operates a switch to open the motor circuit. The switch comprises a head 149 and a disc 177 secured to a sleeve 150 slidable on a terminal rod 153 and a contact member 171 slidable on the sleeve and engaged by housings 174, 180 containing light springs. A stronger spring 178 abuts on disc 177. In the position shown, spring contact arms 164, 165 connected to rod 153 engage a conducting part of member 171 to complete the circuit. When the head 149 is moved by button 148, compression of the spring in housing 180 is followed by positive engagement of the head and housing through a sleeve 152 causing the arms 164, 165 to snap on to a nonconducting part of member 171 thus breaking the circuit. When due to fall of the liquid pressure the button 148 leaves head 149, the reverse action is effected by the spring 178 through disc 177, housing 174 and its spring Normally, the disc valve 72, Fig. 12, being unseated, chamber 49 behind the actuator piston 50 is open to the exhaust reservoir 82 through valve 67, casing 37, port 79 and pipe 81. Depression of the pedal operates arm 76 through floating lever 21, seating valve 72 and sliding valve 67 to connect accumulator chamber 141, Fig. 4, to piston chamber 49 through ports 48, 70, until the hydraulic pressure reacting through the piston area of the valve on the pedal balances the pedal pressure when the ports 70 are again closed. The pressure on piston 50 is transmitted to the brakes through arms 77, 78 and link 19. The pedal pressure is simultaneously transmitted to link 19 through floating lever 21. A similar arrangement for operating a clutch is also shown, the clutch pedal being mounted on the same shaft as the brake pedal and a link extending forwardly to the clutch operating cylinder. An arrangement is also shown in which the pressure of the pedal and of the piston 50 is transmitted to the brakes or clutch by a hydraulic transmission system, link 19 being dispensed with and the lower end of lever 77 engaging both the piston 50 and the piston rod of a master cylinder coaxial with cylinder 46. In this case only the front brake cylinders may be connected to the master cylinder, the rear brake cylinders being directly connected to the chamber 49 of cylinder 46. The circuit of the pump motor 100 may be controlled by the ignition switch of the vehicle and by the clutch or brake pedal as well as by the automatic switch.